This invention relates to a system and method for the automatic control of electrically operated gates and more particularly to a system and method for the automatic control of the opening and closing of gates which is adaptable for use with a wide variety of sizes and types of gates without the need for mechanical adjustments.
Over the years, a variety of types and styles of gates have been developed to provide security for such areas as parking structures and entrances and exits to residential and industrial property. These gates may take the form of sliding gates which move in a track, or swinging gates which are rotatably hinged to a structure. Where large passageways are involved, gates may be provided in pairs which operate from opposite sides of the openings.
Many control systems have been developed to provide automatic control for the opening and closing of gates. These control systems include an electric motor operatively connected to the gate to control its motion. Typically, the motor is controlled by a switch in the vicinity of the gate which can only be operated by authorized personnel. For example, the switch may be in the form of a key switch which can only be operated by use of a conventional key or by a card key. Prior art control systems also employ means for mechanically sensing when the gate is in its fully opened or fully closed position. These sensing means are typically in the form of limit switches which are used to deenergize the motor when the gate has reached its full travel position. The limit switches must be individually adjusted for each gate installation to ensure proper alignment with the opened and closed positions of the gate. In addition, because of the mechanical nature of the limit switches, they tend to wear and change in their adjustment, resulting in improper gate operation.
In addition to detecting the opened and closed positions of the gate, safety considerations require means for detecting if the gate has encountered an obstruction in its travel. For example, such obstructions might be caused by a vehicle or pedestrian in the path of the gate while it is being operated. When an obstruction is detected, gate motion must be stopped to avoid damage to either the gate or the obstruction.
Prior art gate control systems employ several techniques for detecting gate obstruction. One detection technique employs electrical sensors in the form of pressure-actuated electrical switches mounted directly to the gate. When these switches contact an obstruction, they interrupt power to the motor and stop the gate travel. Another detection technique used in prior art gate control systems includes monitoring the electrical current flowing through the motor used to power the gate. When the gate motion is obstructed, the increased load on the motor is reflected by an increase in motor current. This motor current increase is then used as a signal to stop gate travel.
From the above discussion of prior art gate control systems, it can be seen that these systems employ separate and distinct means for sensing the end of travel of the gate, and for sensing gate obstruction. Further, the means for sensing the end of travel of the gate requires individual mechanical adjustments for each gate installation.
It is accordingly an object of the present invention to provide a new and improved system and method for the automatic control of electrically operated gates;
It is another object of the present invention to provide a system and method for the automatic control of gate opening and closing which combines the means for sensing end of travel of the gate with the means for detecting gate obstruction;
It is yet another object of the present invention to provide a new and improved system and method for the automatic control of gate opening and closing which employs means for sensing gate end of travel which is automatically self-adjusting;
It is still another object of the present invention to provide a system and method for the automatic control of gate opening and closing which is adaptable for use with either one or a pair of sliding or swinging gates.